1. Technical Field
The present invention relates to an injection molding machine comprising an injection molding tool having a mold cavity, in which a molded part can be produced by overmolding a mold core made of metal and inserted into the mold cavity using an injection molding material, and a melting tool by means of which the mold core overmolded with the injection molding material can be melted out.
2. Background Information
It is known to produce workpieces having a mostly elongate cavity in an injection molding process using lost-core technology. Examples of workpieces molded by this technology are e.g. intake manifolds for vehicle motors, coolant lines in motor vehicles and the like.
In lost-core technology, a mold core of an easily meltable material (e.g. a bismuth alloy) is produced first and inserted in a mold cavity of an injection-molding mold. Thereafter, the mold core is overmolded with the injection molding material proper and removed from the mold together with the enclosed (solid) mold core. For removing the mold core, it has been common practice in lost-core technology so far to melt out the mold core by immersion of the molded part, that has been removed from the mold, into a bath of a melting liquid (e.g. an alcohol compound commercially offered under the trade name “Lutron” from BASF AG). The liquefied core is then removed and reused for making a new mold core. The molded part is removed from the Lutron bath, cleaned and then processed further.
With conventional injection molding systems used for lost-core technology, it is necessary to have a production line comprising as separate components: an injection molding machine, a core molding machine, a plurality of robots, a core melting bath containing Lutron as melting liquid, a heating for the melting liquid, a large heated container for the melting liquid, a washing means for removing the melting liquid from the molded part, and a drying station for the molded part. Especially the relatively large heated container for the melting liquid as well as the additional precautions for cleaning and drying the workpieces from the melting liquid after the melting operation necessitate corresponding expenditure in terms of space. Such a production line thus is comparatively expensive as regards to both the purchase and the operating costs of the same. Thus, despite qualitatively attractive results, the lost-core technology so far has been deemed uneconomical for many applications, and often other processes (e.g. vibration welding processes) were used instead which, however, did not yield comparable results. The vibration welding technology, used often for the production of molded parts with elongate cavities, such as pipes, for example has the disadvantage that welding flanges are necessary on the workpiece for being able to weld together two workpiece halves. As the welding flanges are protruding from the finished workpiece, they impair the appearance, and in case of narrow installation conditions, as these are frequent in automotive engineering, they lead to problems in terms of space.
Therefore, it would be desirable to be able to produce, by way of lost-core technology, parts used in particular in the field of automotive engineering with reasonable expenditure. It is thus an object of the invention to make available an injection molding system suitable for lost-core technology, which operates with clearly lower expenditure than conventional known systems.